A linear voltage differential transformer position sensor can sense a position of a shaft disposed between a primary winding and secondary windings of the transformer. An excitation signal is applied to the primary winding, and the excitation signal is coupled to the secondary windings. The resulting voltages across the secondary windings can be used to calculate shaft position. One technique to measure the secondary voltages involves calculating the RMS or average value across each secondary winding in response to the excitation signal applied to the primary winding. This method requires collecting several samples during the period of the excitation frequency. Moreover, if the excitation waveform has distortion from an ideal sine wave, the measurement will require many samples to measure the magnitude correctly.
Another measurement technique is to sample twice per cycle, once at the positive peak and once at the negative peak of each of the secondary induced signals, taking the difference between the two measurements. The challenge of this peak-to-peak measurement is to find the peaks of the secondary waveform. There is a phase shift between the excitation voltage of the primary winding and the secondary windings. This phase shift changes as a function of the temperature, aging, interconnect wiring etc., making determination of the peak-to-peak measurement difficult.